FORM AND STRUCTURE OF BACTERIA 23 



There are several modifications in form and function among 

 the higher bacteria. The members of one group (Beggio- 

 toaceae) are free from attachment and usually move by un- 



FIG. 17. The formation of gonidia. (^4) Streptothrix actinomyces, after Leh- 

 mann and Neumann. (B) Streptothrix chromogena, after Mace. (C), (D) 

 Crenothrix Kuhniana, after Kopf : (C) microgonidia ; (D) macrogonidia. () 

 Gonidia-like bodies in Bact. tuberculosis. 



dulative movements of their protoplasm. Some authors 

 have ascribed to them an undulating membrane which during 

 motility alternately contracts and relaxes. There is no 

 common sheath around the cells. The cells contain granules 

 of sulphur. Closely related to the above group is the group 

 Thiothrix. This group is similar in structure to the Beggi- 

 atoaceae, but one end of the filament is attached to some 



